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From: Florian Weimer <fweimer@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>, linuxram@us.ibm.com
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Linux-MM <linux-mm@kvack.org>,
	Dave Hansen <dave.hansen@intel.com>
Subject: Re: pkeys on POWER: Default AMR, UAMOR values
Date: Fri, 18 May 2018 23:13:30 +0200	[thread overview]
Message-ID: <27e01118-be5c-5f90-78b2-56bb69d2ab95@redhat.com> (raw)
In-Reply-To: <CALCETrV_wYPKHna8R2Bu19nsDqF2dJWarLLsyHxbcYD_AgYfPg@mail.gmail.com>

On 05/18/2018 09:39 PM, Andy Lutomirski wrote:
> The difference is that x86 starts out with deny-all instead of allow-all.
> The POWER semantics make it very hard for a multithreaded program to
> meaningfully use protection keys to prevent accidental access to important
> memory.

And you can change access rights for unallocated keys (unallocated at 
thread start time, allocated later) on x86.  I have extended the 
misc/tst-pkeys test to verify that, and it passes on x86, but not on 
POWER, where the access rights are stuck.

I believe this is due to an incorrect UAMOR setting.

Thanks,
Florian

  reply	other threads:[~2018-05-18 21:13 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-18 13:17 pkeys on POWER: Default AMR, UAMOR values Florian Weimer
2018-05-18 14:35 ` Andy Lutomirski
2018-05-18 17:44 ` Ram Pai
2018-05-18 19:39   ` Andy Lutomirski
2018-05-18 21:13     ` Florian Weimer [this message]
2018-05-19  0:52       ` Ram Pai
2018-05-19  5:15         ` Florian Weimer
2018-05-18 21:09   ` Florian Weimer

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